The Database is where the Vaul experiment on upgrades for advanced ground forces.
These buildings resemble a cross between a Terran power generator and a Protoss Cybernetics Core. Within them are thousands of crystal files used to archive data collected from around the universe. Most of the data is on Xel'Naga research of the Protoss and Zerg.
After placing agents within research installations of the most technological species, the Vaul have had access to virtually all classified information on experimental technologies developed recently. Heavy ground weapons and armor are always researched here to prepare for any contingency devised by the three main Koprulu races.